Amp and effects pedal problem

I have currently got a Squier BP15 practice amp, fender jazz bass, boss overdrive pedal and only recently acquired a Dunlop Crybaby 105Q bass wah pedal. Now; when i plug in the overdirve pedal and and JUST the bass it plays fine, good tone and sound out of the amp-well the best i can get anyway! But, when i plug in the wah pedal it all gets ****ed up and starts 2 really crackle and distort, i mean i haven't got the adaptor for it yet - so the battery may be running out. Or, the cacky little amp of mine cannot take the wattage and power - HELP!?